1. Field of the Invention
The present invention relates to a portable terminal, and more particularly, to a push rod which provides driving force to a portable terminal having a pair of housings slidably coupled to each other.
2. Description of the Related Art
A portable terminal is an electronic device which performs a mobile communication function for a user. These days, the portable terminal is not simply used only as a mobile communication device, but performs various complicated functions such as a multimedia function for reproducing a music file, a moving picture file, etc., a banking function, mobile banking, and so forth.
Portable terminals are divided into a bar type, a flip type, and a folder type, depending upon the shapes thereof. Recently, a sliding type portable terminal has been disclosed in the art, and has taken most of the portable terminal market together with the folder type portable terminal.
In the bar type portable terminal, a keypad, an input unit such as a microphone, a display unit, and an output unit such as a speaker are provide to a single housing. Because all components for enabling a mobile communication function are provided in one housing, the bar type portable terminal has a simple construction. However, in order to enable voice conversation, a predetermined distance must be secured between the microphone and the speaker. Therefore, limitations necessarily exist in miniaturizing the portable terminal.
In the flip type portable terminal, a flip cover is rotatably mounted to a bar type terminal body, so that a key input unit such as a keypad is covered by the flip cover in a communication standby mode so as to prevent misoperation of the keypad. Nevertheless, similar to the bar type portable terminal, in the flip type portable terminal, it is difficult to secure a predetermined distance between a microphone and a speaker, and limitations necessarily exist in miniaturizing the portable terminal.
In the folder type portable terminal, a pair of housings are foldably coupled to each other. Since an input unit and an output unit are separately located in the housings, merits are provided in miniaturizing the portable terminal. Moreover, in the folder type portable terminal, a desired distance can be easily secured between a microphone and a speaker. Due to these facts, the folder type portable terminal has taken most of the portable terminal market for a long time.
In the sliding type portable terminal, a pair of housings are slidably coupled to each other. An input unit and an output unit are provided separately to the housings. In particular, a key input unit such as a keypad is opened and closed relying upon the relative sliding movement of the housings so that in a communication standby mode, the misoperation of the key input unit is prevented, and in a communication mode, convenience can be provided in manipulating the keypad while providing merits in miniaturizing the portable terminal. Due to these facts, the sliding type portable terminal now has a greater market share than the folder type portable terminal.
In the sliding type portable terminal, the pair of housings are coupled to each other using a sliding module, and automatic and semiautomatic operations are realized using elastic members. As the elastic members, a torsional coil spring or a push rod is used. Specifically, since the push rod can stably execute sliding operation and provides merits in slimming the portable terminal, the push rod is more frequently used as the elastic member of the sliding module.
FIGS. 1 and 2 illustrate a conventional push rod 10 for a sliding type portable terminal. The push rod 10 has support members 13 which are assembled to a casing 11 to be extended out of and retracted into the casing 11. Rotation members 15 are fastened to outer ends of the support members 13. The rotation members 15 are rotatably coupled to respective housings which constitute the sliding type portable terminal, to serve as means for rotatably coupling the push rod 13 to the respective housings of the portable terminal.
Nonetheless, in the conventional push rod, when the rotation members approach nearest each other within the range in which the housings of the portable terminal are slidingly moved, a problem is caused in that, because the direction of driving force is perpendicular to the moving direction of the housings of the portable terminal, the sliding movement of the housings of the portable terminal is interrupted. That is to say, as the direction, in which the force of the push rod is applied, and the direction, in which the housings of the portable terminal are slidingly moved, are perpendicular to each other, the driving force of the push rod is not properly transmitted to the housings of the portable terminal, and the housings are held in a stopped state.